Various mechanisms exist for secure booting. The unified extensible firmware interface (UEFI) specification defines a model for the interface between operating systems and platform firmware. That interface uses data tables that contain platform-related information, plus boot and run time service calls that are available in the operating system loader. Together these provide a standard environment for booting an operating system and running pre-boot applications. More information about UEFI may be found on the Internet at URL www*uefi*org/home where periods have been replaced with asterisks to prevent inadvertent hyperlinks. The UEFI standard may be used to assist with secure boot of the platform.
Currently different original equipment manufacturers and basic input/output system (BIOS) venders implement different variations of the UEFI firmware. Many of these implementations rely on a system management mode (SMM) feature.
System-on-a-chip based systems use access controlled resources and data that are mainly managed under the control of an inband agent such as UEFI via SMM. Examples include platform UEFI variables, motion energy image (MEI) numbers, medium access control (MAC) address, and various device calibration data which are access controlled data elements of the platform and which need to be managed securely.